Windows software for converting timezones

Is there any very simple Windows software that I can use to very easily convert from UTC to other timezones? For whatever reason I am having a devil of a time finding what I figure is the world's simplest software )

Is there any very simple Windows software that I can use to very easily convert from UTC to other timezones? For whatever reason I am having a devil of a time finding what I figure is the world's simplest software

I suggest you focus on the latter part, and try find out the reason you find it difficult.

What software have you found and (I assume) tried, but found too difficult? (It helps to know what software you've already tried. And it helps to know why they failed in order to understand what your unstated requirements are.)

How do you want to do the conversion? One timestamp at a time, cut and paste? Or do you want to convert a series of timestamps at a single time? Do you want to convert to all kinds of time zone in successive attempts, or do you want one or more 'standard' timezones that, say, 90% of the conversions use? (It helps to know what workflow you're trying to support.)

What format are your UTC timestamps in? ISO? or something else?

Is 'UTC' a strict requirement (i.e. support of leap seconds)?

Do you have any requirements for historical timestamps? I'm thinking of situations where time zone association or rules for daylight savings time has changed over time, and where time zone/DST rules today may not be what was used at the time the timestamp refers to. (You may have included this in your requirements already as you say 'time zone' and not 'local time', I'm just trying to ensure that I'm not overinterpreting.)

As Athulin said we really need more information. But assuming your dates are stored as a numeric value, or ISO8601 text values, and assuming you want to only convert to one timezone (i.e. that set on your computer) you can use an SQLite command line shell.

First get your dates into a CSV file, in the following example I have just one column with a unix 10 digit date

You then need to create an SQLite database and then import the dates into an a table.

The following shows me doing the import into a table called, imaginatively, datestable

The following query shows the raw value, the value converted to UTC and the value converted to local time (currently set to PST on my computer.

This will also work for other date formats i.e. Microsoft filetime, unix millisecs, NSDate etc. using an appropriate conversion.

A complication occurs if you want to display a date in multiple timezones. SQLite only allows UTC and whatever the timezone is set to on your machine at the time the query is run. My Forensic Browser for SQLite has SQL extensions that you can use to display a date in multiple timezones, with or without applying DST. You can also directly specify alternate date formats instead of unixepoch (such as NSDate, Chrome, filetime, OLE etc.)

The format of the date and time in the Browser is picked up from your computers locale settimgs, so if you are in the States etc. the date would likely be the more familiar mm/dd/yyyy.

There are also built in column display conversions in the Browser that enable you to set the displayed date of the column without using SQL (i.e. click on a column and a choose a date format and timezone from a dialog, I have not shown these here).

Much more information on different dates and time in SQLite in my book SQLite Forensics

Many seemingly simple problems are often surprisingly complex. Superficially it's just add or subtract an hour or three and done. But when you factor in how it's going to be used and at what level to do it, the complexity grows. Boundary conditions that roll over days, months (Feb 29), years.

Are you dealing with ASCII string time, Unix seconds from 1970, Excel days from 1901, scaled time in arbitrary lumps such as 100 nanoseconds.

What are the start and end time zones? Are you accounting for daylight savings time on both ends, which is location and time dependent? Do you even know the location to attempt the conversion?

What kind of precision do you need to maintain? Are you accounting for "Leap Seconds", the difference between GPS Time and UTC and therefore Local time.

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I once had a large governmental organization demand that we convert all UTC time stamps to U.S. east coast time because they didn't understand UTC. No amount of explanation about world wide comparison and correlation would sway them. We did it for them, but it wasn't pretty.

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If you should ever try to handle historical data, it gets weird fast as many common tools and databases cannot handle pre-20th Century dates and the very calendar definition goes wonky in the 1600's.

I do use TimeLord, and it is absolutely fantastic software – but I am missing just one tool; and when I use the term "simple," I don't actually mean that. I have great respect for the programming required to deal with the myriad difficulties of Daylight Savings Time and all the nuances involved. I mean "simple" in terms of UI.

I'm looking at a big spreadsheet of dates and times, they look for example, like this

4/30/17 194905

So, I'd like a small tool that essentially does what I am using this website to do, except as a Windows executable that can stay open on the screen

Sometimes the date/time setup won't appear exactly as I showed above, so I don't want to use a fancy conversion tool or script – just a quick program that I can open up, put in a date/time and see an instant conversion from UTC to PST (or whatever other timezone).